Although the amine transaminase from Vibrio fluvialis has often been applied as a catalyst for the biocatalytic preparation of various chiral primary amines, it is not suitable for the transamination of a-hydroxy ketones and aryl-alkyl ketones bearing an alkyl substituent larger than a methyl group. We addressed this problem through a systematic mutagenesis study of active site residues to expand its substrate scope towards two bulky ketones. We identified two mutants (F85L/ V153A and Y150F/V153A) showing 30-fold increased activity in the conversion of (S)-phenylbutylamine and (R)-phenylglycinol, respectively. Notably, they facilitated asymmetric synthesis of these amines with excellent enantiomeric purities of 98 % ee.

This review describes major advances in the use of functionalized molecular metal oxides (polyoxometalates, POMs) as water oxidation catalysts under electrochemical conditions. The fundamentals of POM-based water oxidation are described, together with a brief overview of general approaches to designing POM water oxidation catalysts. Next, the use of POMs for homogeneous, solution-phase water oxidation is described together with a summary of theoretical studies shedding light on the POM-WOC mechanism. This is followed by a discussion of heterogenization of POMs on electrically conductive substrates for technologically more relevant application studies. The stability of POM water oxidation catalysts is discussed, using select examples where detailed data is already available. The review finishes with an outlook on future perspectives and emerging themes in electrocatalytic polyoxometalate-based water oxidation research.

Despite their technological importance for water splitting, the reaction mechanisms of most water oxidation catalysts (WOCs) are poorly understood. This paper combines theoretical and experimental methods to reveal mechanistic insights...

A mild and highly efficient catalytic amination procedure for chloroheteroarenes at ambient temperature using the Pd/PTABS catalytic system is reported. The protocol is selective for the amination of chloroheteroarenes using secondary amines such as piperidine, pyrrolidine, and several others. The exceptional mildness of the developed protocol is beneficial for the synthesis of a crucial Buparlisib intermediate as well as the formal synthesis of Alogliptin in competitive yields.

Molecular metal oxides, or polyoxometalates (POMs) offer unrivalled properties in areas ranging from catalysis and energy conversion through to molecular electronics, biomimetics and theranostics. While POMs are ubiquitous metal oxide model systems studied in most areas of chemistry and materials science, their technological deployment is often hampered by their molecular nature, as this leads to increased degradation, leaching and loss of reactivity, particularly when harsh applications, such as water electrolysis, thermal catalysis or highly basic/acidic reaction solutions are targeted. Therefore, immobilization of POMs on heterogeneous substrates has recently become a central theme in POM research. While early studies focused mainly on metal oxide and semiconductor supports, more recently, POM integration in soft matter matrices including polymers, conductive polymers, hydrogels and stimuliresponsive matrices have led to breakthroughs in multifunctional composite design. This Progress Report will summarize the recent pioneering studies in this emerging field, highlight current challenges which need to be overcome to allow a more widespread technological deployment and provide the authors' view of some of the most promising future directions of the research field. In addition, we provide an unprecedented summary of the correlations between structure (on the molecular, nano-and microscale) and resulting reactivity, so that materials design beyond empirical studies can be further developed. We believe that this timely Progress Report will serve as a focal point to further develop the field, as well as point of reference for newcomers in the area of knowledge-driven bottom up materials design. Given this broad range of interest groups, we believe that Advanced Functional Materials is the ideal journal for this Progress Report.

We report IR and UV/Vis spectroscopic signatures that allow discriminating between the oxidation states of the manganese-based water oxidation catalyst [(Mn 4 O 4 )(V 4 O 13 )(OAc) 3 ] 3À . Simulated IR spectra show that V=O stretching vibrations in the 900-1000 cm À 1 region shift consistently by about 20 cm À 1 per oxidation equivalent. Multiple bands in the 1450-1550 cm À 1 region also change systematically upon oxidation/reduction. The computed UV/Vis spectra predict that the spectral range above 350 nm is characteristic of the managanese-oxo cubane oxidation state, whereas transitions at higher energy are due to the vanadate ligand. The presence of absorption signals above 680 nm is indicative of the presence of Mn III atoms. Spectroelectrochemical measurements of the oxidation from [Mn III 2 Mn IV 2 ] to [Mn IV 4 ] showed that the change in oxidation state can indeed be tracked by both IR and UV/Vis spectroscopy.

Despite their technological importance, reaction mechanisms of most water oxidation catalysts (WOCs) are poorly understood. We combine theoretical and experimental methods to reveal mechanistic insights into the reactivity of the highly active molecular WOC [Mn4V4O17(OAc)3]3-. Using density functional theory, electrochemistry and IR-spectroscopy, we propose a three-step activation mechanism: one-electron oxidation [Mn3+2Mn4+2]→[Mn3+Mn4+3], acetate-to-water ligand exchange, and another one-electron oxidation [Mn3+Mn4+3]→[Mn4+4]. Analysis of ligand exchange pathways shows that nucleophilic attack of water molecules along the Jahn-Teller axis of Mn3+ centers leads to lower activation barriers than attack at Mn4+ centers. Deprotonation of one water ligand by the leaving acetate group leads to formation of the activated species [Mn4V4O17(OAc)2(H2O)(OH)]1-. Computed Redox potentials are in excellent agreement with electrochemical measurements. This interplay between redox chemistry and ligand exchange controls the formation of the catalytically active species. These results provide key reactivity information essential to further study bio-inspired molecular WOCs and solid-state manganese oxide catalysts.

A {Cu4(μ3-OH)4} compound, where four copper(II) and four μ3-bridging oxygen atoms occupy alternate corners of a slightly distorted cube, has been prepared and structurally characterized. This species, formulated as [Cu4(μ3-OH)4(Htmpz)8](ClO4)4·1.5Et2O (Htmpz = 3,4,5-1H-trimethyl pyrazole), can be classified as belonging to type I Cu4O4 cubane complexes, and is better described as two Cu(II)-(μ-OH)2-Cu(II) units held together by four long Cu-O bonds. The central distorted cubane core is stabilized by neutral monodentate ligands (Htmpz) and perchlorate anions, as demonstrated by single-crystal X-ray structure analysis. The title compound was obtained by hydrolysis of a dinuclear methoxo-bridged species, [Cu(μ-OCH3)(Htmpz)2]2(ClO4)2, which was prepared by reaction of [Cu(Htmpz)4(ClO4)2] with methanol. All these reactions represent a nice example of the Goldilocks principle in action in coordination chemistry, since each single actor (solvent, counteranion, and ligand) has the "just right" electronic, steric or coordinative properties which determine the fate of the final products.